It is well known to establish wireless communication channels between two devices in order to transfer data between the devices. For example, a Bluetooth protocol may be used to transfer data between two devices that are relatively close to each other. According to Bluetooth protocols, when it is desired to transfer data from a first device to a second device the first device is operated in an advertising state. In this state, the first device broadcasts advertising channel packets that indicate that the first device has data to transfer to another device. The second device is operated in a scanning state so as to listen for advertising channel packets from other devices. When the second device receives an advertising channel packet from the first device, then the second device will ultimately send a connection request message to the first device in order to set up a bi-directional data connection between the two devices. A data connection is formed by the transceivers of the two devices being tuned to the same frequency channel at the same time. The data may then be transferred from the first device to the second device through the data connection
Such communication protocols, particularly the Bluetooth Low Energy (BLE) protocol, which is part of the Bluetooth v 4.0 protocol, require a relatively small amount of power to transfer data. However, it is still desired to provide data communication between devices using techniques that use even lower amounts of power. This is particularly the case in mobile devices, which tend to have relatively low capacity batteries due to size restrictions and which are becoming more power hungry as they are increasing in functionality. Even if a relatively small amount of data is required to be transferred between the devices, the power usage by conventional communication techniques may be considered excessive in some applications.
By way of example, in recent years global navigation satellite systems, e.g. GPS, devices have started to be used for pedestrian and outdoor applications. For example, fitness watches that include GPS receivers have started to be used by joggers, runners, cyclists and other athletes and outdoor enthusiasts as a means to obtain real-time data of their speed, distance travelled, etc. It may be desirable during group activities to transfer data from one person's fitness watch to another person's fitness watch. For example, it may be desirable during a competition for each competitors watch to transfer data regarding their position to the other competitors' watches so that each competitors watch is able to display their location relative to that of the other competitors. However, fitness watches are relatively power hungry due in part to the GPS receivers contain therein, and such data transfers only serve to drain the batteries even faster. Fitness watches only contain relatively low capacity batteries as they are desired to be small and light devices. As such, the above-described data communication with other fitness watches may be seen as prohibitive as it would reduce the length of the battery life between recharges.
Another problem with some conventional communication techniques such as Bluetooth devices is that the Bluetooth chip is typically only able to establish a few data connection channels at any given time. If all of such data channels are already in use then it has conventionally been considered not possible to transfer data to or from that device. For example, a conventional fitness watch may have established a Bluetooth connection with a heart rate monitor and a foot pod sensor, thereby occupying all of its data channels and leaving no data channels for transferring other data to or from the fitness watch.
It is desired to provide an improved method and devices for communicating data from a sensor between two devices.